public class MyLinkedList implements IList{
    static class ListNode{
        public int val;
        public ListNode prev;
        public ListNode next;
        public  ListNode(int val){
            this.val = val;
        }
    }
    public ListNode head;
    public ListNode last;
    @Override
    public void addFist(int data) {
        ListNode node = new ListNode(data);
        if (head == null){
            head = node;
            last = node;
        }else{
            node.next = head;
            head.prev = node;
            head = node;
        }
    }

    @Override
    public void addLast(int data) {
        ListNode node = new ListNode(data);
        if (head == null){
            head = node;
            last = node;
        }else{
            node.prev = last;
            last.next = node;
            last = node;
        }
    }

    @Override
    public void Index(int index, int data) {
        if (index < 0 || index > size()){
            throw new IndexException("双向链表插入,index" + index+"不合法");
        }
        if (index == 0){
            addFist(data);
            return;
        }
        if (index == size()){
            addLast(data);
            return;
        }
        ListNode cur = findIndex(index);;
        ListNode node = new ListNode(data);

        node.next = cur;

        cur.prev.next = node;
        node.prev = cur.prev;
        cur.prev = node;

    }

    private ListNode findIndex(int index){
        ListNode cur = head;
        while(index != 0){
            cur = cur.next;
            index--;
        }
        return cur;
    }

    @Override
    public boolean contains(int key) {
        ListNode cur = head;
        while(cur.next != null){
            if(cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    @Override
    public void remove(int key) {
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
//                删除头结点
                if (cur == head){
                    head = head.next;
//                  如果只有一个节点
                    if (head != null){
                        head.prev = null;
                    }else {
                        last = null;
                    }
                    return;
                } else if (cur == last){
//                    删除尾结点
                    last = last.prev;
                    last.next = null;
                    return;
                }else {
//                    删除中间节点
                    cur.prev.next = cur.next;
                    cur.next.prev = cur.prev;
                    return;
                }
                }
            cur = cur.next;
        }
    }


    @Override
    public void removeAllKey(int key) {
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
//                删除头结点
                if (cur == head){
                    head = head.next;
//                  如果只有一个节点
                    if (head != null){
                        head.prev = null;
                    }else {
                        last = null;
                    }
                } else if (cur == last){
//                    删除尾结点
                    last = last.prev;
                    last.next = null;
                }else {
//                    删除中间节点
                    cur.prev.next = cur.next;
                    cur.next.prev = cur.prev;
                }
            }
            cur = cur.next;
        }
    }

    @Override
    public int size() {
        int count = 0;
        ListNode cur = head;
        while(cur.next != null){
            count++;
            cur = cur.next;
        }
        return count;
    }

    @Override
    public void clear() {
        ListNode cur = head;
        ListNode curNext = cur.next;
        while(cur != null){
            curNext = cur.next;
            cur .prev = null;
            cur = curNext;
        }
        this.head = null;
        this.last =  null;
    }

    @Override
    public void display() {
        ListNode cur = head;
        while(cur != null){
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
        System.out.println();
    }
}
